A Level Chemistry 9701 Paper 22, May/June 2024

Complete Table 1.1 using relevant information from the Periodic Table. Table 1.1

State and explain the difference in the ionic radius of ${\mathrm{A}\mathrm{l}}^{3+}$ compared to ${\mathrm{M}\mathrm{g}}^{2+}$.

Draw a labelled diagram to show the structure and bonding in sodium.

Fig. 1.1 shows the variation in melting point of some Period 3 elements in their standard states at room temperature and pressure. Explain why Si has a high melting point.

Complete Fig. 1.1 to show the variation in the melting points of the elements P, S and Cl.

Two Period 3 elements react with an excess of oxygen at room pressure. Complete Table 1.2. Table 1.2

The solutions made in column 3 of Table 1.2 are mixed together. Name the type of reaction that occurs.

Write an equation to describe the reaction between ${\mathrm{P}}_4{\mathrm{O}}_{10}$ and an excess of water.

Aluminium hydroxide is amphoteric. Explain what is meant by amphoteric.

Write an equation to describe the reaction that occurs when aluminium hydroxide, $\mathrm{A}\mathrm{l}(\mathrm{O}\mathrm{H}{)}_3$, reacts with $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$.

Complete the reaction pathway diagram in Fig. 2.1 for reaction 2. Label the diagram to show the enthalpy change, $\mathrm{\Delta }{H}_2$, and the activation energy, $E_{\mathrm{A}}$.

The value for $\mathrm{\Delta }{H}_1$ is determined by experiment using the following method. • $50.0\mathrm{c}{\mathrm{m}}^3$ of $2.00\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{d}{\mathrm{m}}^{-3}\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q})$ is added to a polystyrene cup. • The initial temperature of the acid is recorded as $19.6{}^{\circ }\mathrm{C}$. • $0.0400\mathrm{m}\mathrm{o}\mathrm{l}$ of $\mathrm{N}{\mathrm{a}}_2\mathrm{C}{\mathrm{O}}_3$ is added and the mixture is stirred. • All the solid $\mathrm{N}{\mathrm{a}}_2\mathrm{C}{\mathrm{O}}_3$ disappears and a colourless solution is produced. The maximum temperature recorded during the reaction is $26.2{}^{\circ }\mathrm{C}$. Describe one other observation that shows the reaction is complete.

Calculate the value of $\mathrm{\Delta }{H}_1$ in $\mathrm{k}\mathrm{J}\mathrm{m}\mathrm{o}{\mathrm{l}}^{-1}$. Assume the specific heat capacity of the reaction mixture is the same as for water and no heat is lost to the surroundings. Show your working. $\mathrm{\Delta }{H}_1=\text{.............................. }\mathrm{k}\mathrm{J}\mathrm{m}\mathrm{o}{\mathrm{l}}^{-1}$

Thermal decomposition occurs when $\mathrm{N}\mathrm{a}\mathrm{H}\mathrm{C}{\mathrm{O}}_3$ is heated. reaction 3 $2\mathrm{N}\mathrm{a}\mathrm{H}\mathrm{C}{\mathrm{O}}_3\to \mathrm{N}{\mathrm{a}}_2\mathrm{C}{\mathrm{O}}_3+{\mathrm{H}}_2\mathrm{O}+\mathrm{C}{\mathrm{O}}_2$ Calculate the enthalpy change for reaction 3, $\mathrm{\Delta }{H}_{\mathrm{r}}$, using the data in Table 2.1 and the value of $\mathrm{\Delta }{H}_1$ calculated in (b)(ii). (If you were unable to calculate a value for $\mathrm{\Delta }{H}_1$ in (b)(ii), assume the enthalpy change is $-38.4\mathrm{k}\mathrm{J}\mathrm{m}\mathrm{o}{\mathrm{l}}^{-1}$. This is not the correct value.) $\mathrm{\Delta }{H}_{\mathrm{r}}=\text{.............................. }\mathrm{k}\mathrm{J}\mathrm{m}\mathrm{o}{\mathrm{l}}^{-1}$

Z is a salt that contains a Period 4 element from Group 2. When Z is heated brown gas forms. Identify the formula of Z and use it to write an equation for the reaction.

Describe what is meant by dynamic equilibrium.

Reaction 4 describes the reversible reaction between yellow $\mathrm{F}{\mathrm{e}}^{3+}(\mathrm{a}\mathrm{q})$ and colourless $\mathrm{S}\mathrm{C}{\mathrm{N}}^{-}(\mathrm{a}\mathrm{q})$ to produce red $\mathrm{F}\mathrm{e}\mathrm{S}\mathrm{C}{\mathrm{N}}^{2+}(\mathrm{a}\mathrm{q})$.

An equilibrium mixture contains $\mathrm{F}{\mathrm{e}}^{3+}(\mathrm{a}\mathrm{q})$, $\mathrm{S}\mathrm{C}{\mathrm{N}}^{-}(\mathrm{a}\mathrm{q})$ and $\mathrm{F}\mathrm{e}\mathrm{S}\mathrm{C}{\mathrm{N}}^{2+}(\mathrm{a}\mathrm{q})$. A few colourless crystals of soluble $\mathrm{K}\mathrm{S}\mathrm{C}\mathrm{N}(\mathrm{s})$ are added. The mixture is then left until it reaches equilibrium again. The temperature of both equilibrium mixtures is the same. Deduce the changes that occur, if any, in the equilibrium mixture after $\mathrm{K}\mathrm{S}\mathrm{C}\mathrm{N}(\mathrm{s})$ is added compared to the original equilibrium mixture. • change in appearance • change in relative concentration of $\mathrm{F}{\mathrm{e}}^{3+}(\mathrm{a}\mathrm{q})$ • change in value of the equilibrium constant, $K_{\mathrm{c}}$

The expression for the equilibrium constant, $K_{\mathrm{c}}$, for reaction 4 is shown. $$K_{\mathrm{c}}=\frac{[\mathrm{F}\mathrm{e}\mathrm{S}\mathrm{C}{\mathrm{N}}^{2+}(\mathrm{a}\mathrm{q})]}{[\mathrm{F}{\mathrm{e}}^{3+}(\mathrm{a}\mathrm{q})]\times [\mathrm{S}\mathrm{C}{\mathrm{N}}^{-}(\mathrm{a}\mathrm{q})]}$$ $5.00\times {10}^{-5}\mathrm{m}\mathrm{o}\mathrm{l}$ of $\mathrm{F}{\mathrm{e}}^{3+}(\mathrm{a}\mathrm{q})$ and $5.00\times {10}^{-5}\mathrm{m}\mathrm{o}\mathrm{l}$ of $\mathrm{S}\mathrm{C}{\mathrm{N}}^{-}(\mathrm{a}\mathrm{q})$ are added together and allowed to reach equilibrium. The total volume of the mixture is $25.0\mathrm{c}{\mathrm{m}}^3$. At equilibrium the concentration of $\mathrm{F}\mathrm{e}\mathrm{S}\mathrm{C}{\mathrm{N}}^{2+}(\mathrm{a}\mathrm{q})$ is $4.23\times {10}^{-4}\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{d}{\mathrm{m}}^{-3}$. Calculate the equilibrium constant, $K_{\mathrm{c}}$, for reaction 4. Include the units in your answer. $K_{\mathrm{c}}=\text{..............................}$ units $\text{..............................}$

Determine the full electronic configuration of $\mathrm{F}{\mathrm{e}}^{3+}$.

$\mathrm{S}\mathrm{C}{\mathrm{N}}^{-}(\mathrm{a}\mathrm{q})$ is colourless. Complete the dot-and-cross diagram in Fig. 3.1 to show the arrangement of outer electrons in an $\mathrm{S}\mathrm{C}{\mathrm{N}}^{-}$ ion.

Draw the three-dimensional structures of the two stereoisomers of $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}\mathrm{C}{\mathrm{H}}_3$. R can be used to represent $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5$.

A sample of $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}\mathrm{C}{\mathrm{H}}_3$ reacts with $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$ to make $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{C}{\mathrm{H}}_3$ in an ${\mathrm{S}}_{\mathrm{N}}1$ mechanism. Complete Fig. 4.1 to show the mechanism for the reaction of $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}\mathrm{C}{\mathrm{H}}_3$ and $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate.

Separate samples of $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}\mathrm{C}{\mathrm{H}}_3$, $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{C}{\mathrm{H}}_3$ and $\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{H}}_2$ are tested with different reagents. Complete Table 4.1. If no reaction occurs, write $\times$ in the relevant box. Table 4.1

$\mathrm{C}{\mathrm{H}}_3(\mathrm{C}{\mathrm{H}}_2{)}_5\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}\mathrm{C}{\mathrm{H}}_3$ is heated with D to produce three different molecules, E, F and G. Name the type of reaction.

Identify D and the conditions used.

Both $\sigma$ and $\pi$ bonds are present in a molecule of E as a result of different types of hybridisation in the carbon atoms. Complete Table 4.2 to show the number of carbon atoms with each type of hybridisation in a molecule of E. Table 4.2

Describe the essential feature of an unbranched hydrocarbon that causes its molecules to show stereoisomerism. Explain how this feature leads to stereoisomerism.